I've got 115 unit tests right now, so perhaps not that many compared to some. But there still seems to be a pretty large time gap.
Running with python -m pytest test/unit takes 58.3 seconds.
Running with ./pants --debug test/unit:: takes 4 minutes and 1 second.
I realize that using the --debug option disables caching and parallelism, but I thought it was a good way to get a fair comparison. After all, we could get caching and parallelism outside of pants by using the pytest-testmon and pytest-xdist plugins.